Unraveling the intrinsic mechanism behind the retention of arsenic in the co-gasification of coal and sewage sludge: Focus on the role of Ca and Fe compounds.

Minimizing the emission of arsenic (As) is one of the urgent problems during co-gasification of Shenmu coal (SM) and sewage sludge (SS). The intrinsic mechanism of As retention was obtained by analyzing the effect of different SM addition ratios on the As form transformation during co-gasification at 1000 °C under CO2 atmosphere. The results showed that the addition of SM effectively promoted the enrichment of As in the co-gasified residues. Especially, the best As retention rate of 65.71% was achieved with the 70 wt% addition ratio of SM. The addition of SM promoted the adsorption and chemical oxidation of As(III) to the less toxic As(V) through the coupling of Ca and Fe compounds in the co-gasified residues. XRD and XPS results indicated that Fe2O3 adsorbed As2O3(g) after partial conversion to Fe3O4 by the Boudouard reaction, while part of As2O3 was oxidized to As2O5 by lattice oxygen. Finally, the generated As2O5 was successively trapped by CaO and Fe2O3 to form stable Ca3(AsO4)2 and FeAsO4. HRTEM and TEM analysis comprehensively proved that As(III) was stabilized by the lattice cage of CaAl2Si2O8. In conclusion, the co-oxidation of Ca and Fe compounds and lattice stabilization simultaneously played a crucial role in the retention of As2O3(g) during co-gasification.

Genome-Wide Identification, Expression and Evolution Analysis of m6A Writers, Readers and Erasers in Aegilops_tauschii.

N6-methyladenosine modifications (m6A) is one of the most abundant and prevalent post-transcriptional RNA modifications in plants, playing the crucial role in plant growth and development and stress adaptation. However, the m6A regulatory machinery in Aegilops_tauschii, the D genome progenitor of common wheat, is not well understood at present. Here, we systematically identified the m6A-related genes in Aegilops with a genome-wide search approach. In total, 25 putative m6A genes composed of 5 writers, 13 readers and 7 erasers were obtained. A phylogenetic analysis clearly grouped them into three subfamilies with the same subfamily showing similar gene structures and conserved domains. These m6A genes were found to contain a large number of cis-acting elements associating with plant hormones, regulation of growth and development as well as stress response, suggesting their widespread regulation function. Furthermore, the expression profiling of them was investigated using RNA-seq data to obtain stress-responsive candidates, of which 5 were further validated with a qPCR analysis. Finally, the genetic variation of m6A-related genes was investigated between Aegilops and D subgenome of wheat based on re-sequencing data, and an obvious genetic bottleneck occurred on them during the wheat domestication process. The promising haplotype association with domestication and agronomic traits was also detected. This study provided some insights on the genomic organization and evolutionary features of m6A-related genes in Aegilops, which will facilitate the further functional study and also contribute to broaden the genetic basis for genetic improvement in wheat and other crops.

Genome-Wide Identification, Evolution and Expressional Analysis of OSCA Gene Family in Barley (Hordeum vulgare L.).

The hyperosmolality-gated calcium-permeable channel gene family (OSCA) is one kind of conserved osmosensors, playing a crucial role in maintaining ion and water homeostasis and protecting cellular stability from the damage of hypertonic stress. Although it has been systematically characterized in diverse plants, it is necessary to explore the role of the OSCA family in barley, especially its importance in regulating abiotic stress response. In this study, a total of 13 OSCA genes (HvOSCAs) were identified in barley through an in silico genome search method, which were clustered into 4 clades based on phylogenetic relationships with members in the same clade showing similar protein structures and conserved motif compositions. These HvOSCAs had many cis-regulatory elements related to various abiotic stress, such as MBS and ARE, indicating their potential roles in abiotic stress regulation. Furthermore, their expression patterns were systematically detected under diverse stresses using RNA-seq data and qRT-PCR methods. All of these 13 HvOSCAs were significantly induced by drought, cold, salt and ABA treatment, demonstrating their functions in osmotic regulation. Finally, the genetic variations of the HvOSCAs were investigated using the re-sequencing data, and their nucleotide diversity in wild barley and landrace populations were 0.4966 × 10-3 and 0.391 × 10-3, respectively, indicating that a genetic bottleneck has occurred in the OSCA family during the barley evolution process. This study evaluated the genomic organization, evolutionary relationship and genetic expression of the OSCA family in barley, which not only provides potential candidates for further functional genomic study, but also contributes to genetically improving stress tolerance in barley and other crops.

Population transcriptomic analysis identifies the comprehensive lncRNAs landscape of spike in wheat (Triticum aestivum L.).

BACKGROUND: Long noncoding RNAs (lncRNAs) are emerging as the important regulators involving in growth and development as well as stress response in plants. However, current lncRNA studies were mainly performed at the individual level and the significance of it is not well understood in wheat. RESULTS: In this study, the lncRNA landscape of wheat spike was characterized through analysing a total of 186 spike RNA-seq datasets from 93 wheat genotypes. A total of 35,913 lncRNAs as well as 1,619 lncRNA-mRNA pairs comprised of 443 lncRNAs and 464 mRNAs were obtained. Compared to coding genes, these lncRNAs displayed rather low conservation among wheat and other gramineous species. Based on re-sequencing data, the genetic variations of these lncRNA were investigated and obvious genetic bottleneck were found on them during wheat domestication process. Furthermore, 122 lncRNAs were found to act as ceRNA to regulate endogenous competition. Finally, association and co-localization analysis of the candidate lncRNA-mRNA pairs identified 170 lncRNAs and 167 target mRNAs significantly associated with spike-related traits, including lncRNA.127690.1/TraesCS2A02G518500.1 (PMEI) and lncRNA.104854.1/TraesCS6A02G050300.1 (ATG5) associated with heading date and spike length, respectively. CONCLUSIONS: This study reported the lncRNA landscape of wheat spike through the population transcriptome analysis, which not only contribute to better understand the wheat evolution from the perspective of lncRNA, but also lay the foundation for revealing roles of lncRNA playing in spike development.

Genome-Wide Identification and Characterization of RNA/DNA Differences Associated with Drought Response in Wheat.

RNA/DNA difference (RDD) is a post-transcriptional RNA modification to enrich genetic information, widely involved in regulating diverse biological processes in eukaryotes. RDDs in the wheat nuclear genome, especially those associated with drought response or tolerance, were not well studied up to now. In this study, we investigated the RDDs related to drought response based on the RNA-seq data of drought-stressed and control samples in wheat. In total, 21,782 unique RDDs were identified, of which 265 were found to be drought-induced, representing the first drought-responsive RDD landscape in the wheat nuclear genome. The drought-responsive RDDs were located in 69 genes, of which 35 were differentially expressed under drought stress. Furthermore, the effects of RNA/DNA differences were investigated, showing that they could result in changes of RNA secondary structure, miRNA-target binding as well as protein conserved domains in the RDD-containing genes. In particular, the A to C mutation in TraesCS2A02G053100 (orthology to OsRLCK) led to the loss of tae-miR9657b-5p targeting, indicating that RNA/DNA difference might mediate miRNA to regulate the drought-response process. This study reported the first drought-responsive RDDs in the wheat nuclear genome. It sheds light on the roles of RDD in drought tolerance, and may also contribute to wheat genetic improvement based on epi-transcriptome methods.

Mesophyll conductance, photoprotective process and optimal N partitioning are essential to the maintenance of photosynthesis at N deficient condition in a wheat yellow-green mutant (Triticum aestivum L.).

The major effect of nitrogen (N) deficiency is the inhibition on CO2 assimilation regulated by light energy absorption, transport and conversion, as well as N allocation. In this study, a yellow-green wheat mutant (Jimai5265yg) and its wild type (Jimai5265, WT) were compared between 0 mM N (N0) and 14 mM N (N14) treatments using hydroponic experiments. The mutant exhibited higher photosynthetic efficiency (An) than WT despite low chlorophyll (Chl) content in non-stressed conditions. The photosynthetic advantages of the mutant were maintained under N deficient condition. The quantitative analysis of limitations to photosynthesis revealed that CO2 diffusion associated with mesophyll conductance (gm) was the dominant limitation. Relative easiness to gain CO2 in the chloroplast contributed to the higher An of Jimai5265yg. N deficiency induced the photoinhibition of PSII, but the cyclic electron transport and photochemical activity of PSI was higher in Jimai5265yg compared to Jimai5265, which was a protective mechanism to avoid photodamage. Because of the sharp drop of An, N deficient seedlings had much lower photosynthetic N use efficiency (PNUE). However, N deficiency increased the relative content of photosynthetic N (Npsn) and decreased the relative content of storage N (Nstore). The range of change in N partitioning induced by N deficiency was smaller for Jimai5265yg compared to WT. The less insensitive to N deficiency for the mutant in terms of photosynthetic property and N partitioning suggested that gm, cyclic electron transport around PSI and more optimal N partitioning pattern is necessary to sustain photosynthesis under N deficient condition.